From left, physicists Naughton, Ren, and Kempa in Boston College’s clean room, where some of the work on their novel solar cell took place. Photograph: Gary Wayne Gilbert.

The item on the Greentech Media website appeared in early July 2010, with the doctored photo of a granite headstone that read “Startup Solasta . . . Closed Its Doors/Sold Its Assets RIP.” Below that somber image, reporter Eric Wesoff’s story explained how, despite $3.6 million in U.S. government grants and an ingenious technology developed by three Boston College professors, the Newton, Massachusetts, photovoltaics company Solasta had gone out of business after fewer than four years in existence, ordered to cease all operations by its sole investor, a venture capital firm. “The wrenching process of startup closure is a difficult and inevitable part of the innovation culture in the United States,” Wesoff wrote, before concluding breezily that “the investors will go on to fund more companies and the entrepreneurs will continue to innovate.”

Wesoff’s assessment is hard to dispute. Yet viewed another way, Solasta’s demise, along with the selloff of its laboratory equipment and the licensing of its advanced technology to South China Normal University in Guangzhou, raises questions about the prevailing “innovation culture,” particularly in renewable energy, where so much depends on shifting market conditions and the actions of governments. Examined closely, Solasta’s downfall, following its promising beginnings in 2006, is not a story of the everyday failure of dreams, and maybe not a story of failure at all. Rather it’s a messy, sometimes maddening tale of high expectations, of breakthroughs trailed by months of frustration, of technical problems that appear mysteriously and disappear just as inexplicably, and (not least) of the challenges of working with devices so tiny they cannot be seen without an electron microscope.

Above all, perhaps, the events surrounding Solasta offer a glimpse of what can happen when scientific motives meet, and clash with, commercial ones. In this story, and presumably others like it, the scientists favor a methodical development process in which each step brings increased understanding of their new device and the underlying physics, while the venture capitalists push hard for quick results. Would slow and steady development have produced success sooner than an all-out race to marketability? The scientists and venture capitalists do not agree.

 

The story of Solasta begins with a chat, probably in early 2004, between physics professors Kryzstof Kempa and Zhifeng Ren. Both scientists had found their way to Boston College’s faculty after growing up in communist societies, but in other ways they make for a study in contrasts. Of the three Solasta founders, Kempa, Ren, and physics department chair Michael Naughton, Kris Kempa is the only one with a parent who worked in a professional occupation. When Kempa was young, his father, an electrical engineer, set up a radio repair shop in their small Polish town, an enterprise frowned upon by the government, which discouraged private business. Kempa’s father then found work at a power company, but he still liked to tinker with radio equipment. Father and son built an amateur radio transmitter together. “It was quite interesting,” Kempa says, “because in communist Poland talking to people across the Atlantic was not the most politically correct thing to do. The secret police would come around and ask us, ‘What the hell are you doing in there?’”

Kempa followed his father’s path to engineering school but switched to theoretical physics for his doctorate. He won a postdoctoral fellowship in West Berlin, slated to start in 1981, but in that Cold War year, he says, Polish authorities “considered my fellowship in [the West] an insult.” Kempa sneaked into West Berlin on a tour bus. He wasn’t allowed into Poland again until after the communist government fell, in 1990, by which time he was already living in the United States and teaching at Boston College.

 

Kempa is solidly built and of above average height, and he tends to speak his mind. His friend and business partner Zhifeng Ren is soft-spoken, slight, and diminutive. Unlike the theoretician Kempa, Ren, who has his name on more than 20 patents and pending patents, says his work is aimed directly at improving people’s lives. “Theoretical work is fun and important,” he explains, “but [making] useful products is the ultimate goal.”

Ren’s background may explain this emphasis. A farmer’s son, he grew up in China’s Sichuan province, in a house with a dirt floor and no plumbing. Sometimes food was scarce, and the family got by on two meals a day. As a boy Ren benefited from a change in Chinese education that came in 1976, after Mao Zedong’s death. Before then, he says, “There was no formal system for college entrance. There was an informal recommendation system, and that was corrupted. If your parents were members of the Communist Party, you could go to college.” Ren tested into high school in 1978, and into college in 1980. By 1990 he had a master’s degrees in materials science and a Ph.D. in physics. Asked how he chose these fields, he says, “I didn’t have a choice. . . . Whatever we were assigned to study, we just put our heart into it.”

Ren arrived at Boston College in 1999, after several years at the State University of New York in Buffalo, where Mike Naughton also taught. Over the years, Ren had developed a specialty in growing nanotube arrays, tiny forests of carbon fibers 100 nanometers thick—about one thousandth the diameter of a human hair. Because matter at the nanoscale takes on unusual properties, including unusual mechanical strength and efficient electrical and heat conduction, nanotube arrays have applications and potential applications in products from textiles to transistors and fields from building to reconstructive medicine. In 2000 Ren and Kempa started a small firm, NanoLab, to manufacture nanotubes for sale to other researchers and to look for novel applications.

One day, the pair were talking casually, says Kempa: “I suggested to Zhifeng a crazy thing—that if you think about a radio antenna, it’s a piece of wire, the length comparable to a wavelength of a radio wave.” What kind of radiation, Kempa asked, has a wavelength comparable to the length of a carbon nanotube?

The answer, as any physicist knows, is visible light, with a wavelength in the hundreds of nanometers. Soon, the two were capturing light with nanotube antennas. The innovation led to an article in the September 2004 Applied Physics Letters, which in turn led to notice in media such as CNN.com and Reuters.

Making headlines was, of course, terrific, but what real good was a nano-antenna? Getting to an answer involved a few steps. Naughton and Kempa thought the light that the nano-antennas captured was being converted to heat energy, which then dissipated into the air. What about coating the nanotubes with a photovoltaic material such as silicon, so that the light could be converted to electrical energy instead? That sounded good, but one big problem remained: how to harvest the electrical energy so that you could use it for power. Kempa came up with a plausible solution, a metal conductor that would be laid over the silicon, creating a nanoscale coaxial cable, a tiny relative of the wires that carry TV signals from the cable company. Interviewed in August 2006, a year or so after that chat with Kempa, Naughton called this insight “the Eureka moment.”

After that, Naughton says, the pair discussed the nanocoax almost every day, eventually leading to another crucial insight: The nanocoax-based solar device could solve the problem that makes conventional solar cells so inefficient—the thick-thin problem.

 

Today’s commercial solar cell, the kind that makes up the solar panel installed atop your neighbor’s roof, consists of a slab of silicon sandwiched between two metal electrical conductors, the top conductor in the form of a grid. When light penetrates the grid and hits the silicon, it knocks an electron off each silicon atom it impinges on, so that light energy is converted to electrical energy. Ideally, each electron thus freed would migrate to one of the metal conductors, and thus an electrical current would flow. In the real world, however, this happens rarely, with most electrons simply wandering around in the silicon, never getting as far as the conductor.

That’s where the thick-thin dilemma comes in. The thicker the silicon, the less likely it is that the electrons will be harvested—will make it out of the silicon and contribute to the flow of electrical current. The thinner the silicon, however, the less light the cell is likely to absorb in the first place, and thus the fewer free electrons available for harvesting. Traditional solar cells, then, represent a compromise, their silicon thick enough to absorb a modest amount of light but thin enough to allow the harvesting of a modest number of electrons. Because of this compromise, their efficiency—the proportion of available light they convert to electricity—ranges from less than 5 percent to a still-low 30 percent.

The nanocoax-based solar cell would work quite differently, absorbing light along the nanotube’s 10,000-nanometer length (thick) while allowing the electrons to migrate to the metal layers across the tube’s 50-nanometer radius (thin). The design represented not a compromise but something much closer to optimal dimensions, both for light absorption and electron harvesting. Moreover, the design should work equally well with the cheap amorphous form of silicon as with the pricier crystalline form.

Kempa’s notion, then, promised to turn the photovoltaics world on its head.

Electron microscope images of a complete nanocoax solar cell, at the edge of the cell array (top) and in a tilted close-up (bottom). Their true color, viewed with the eye, would be pitch black. Photographs: Jakub Rybczynski

 

Kempa and his colleagues thought enough of the idea to fool with it in the laboratory. In late 2005, Kempa, with help from Naughton, wrote a proposal for grant money in a competition run by a state agency, the Massachusetts Technology Transfer Council; the proposal was funded for $25,000. The physicists, along with Jakub Rybczynski, a postdoctoral fellow from Poland, entered a second contest, the Ignite Clean Energy Business Plan Competition, sponsored by the MIT Enterprise Forum. In May 2006, the announcement came that the new solar cell design had taken second place, with a prize of cash and in-kind support valued at $35,000. That spring, Kempa, Ren, and Naughton incorporated as Solasta. The name came from Solas, a bar in Boston’s Back Bay neighborhood where Naughton had recently stopped in for a beer.

More important than the remittances, the wins attracted venture capitalists. The technology drew so much interest, in fact, that for two months in early 2006, between in-person visits and telephone calls from some 20 venture capital firms, the physicists were “ready to drop,” said Naughton, who had emerged as the group’s informal leader.

“It’s crazy! We can’t get rid of them,” Kempa groused. What was scheduled to be a 10-minute call with one suitor, he said, turned into an hour: “It started with ‘That’s very interesting. I’ll send someone out’ and ended with ‘I’m coming out tomorrow!’”

This particular investor, though, wasn’t one whom the physicists wanted to be rid of. Bill Joy was something of a legend in his field, touted in the business press as “the Edison of the Internet” for his visionary software. In Silicon Valley, writes Malcolm Gladwell in his 2008 book Outliers, Joy engendered the same awe as Microsoft’s Bill Gates, having played a central role in developing the Java programming language as well as Berkeley Unix, ancestor of the Unix operating system.

In 2005, figuring that green technology was the economy’s next big act, Joy had become a partner in Kleiner Perkins Caulfield & Byers—KP, for short. This was a venture capital firm with the foresight to have bankrolled Amazon and Google in those corporations’ infancy.

In June 2006, the Boston College physicists signed a term sheet, an agreement whereby KP would invest $4 million in exchange for preferred stock amounting to half of their company. Interviewed that August, Naughton explained that he liked KP’s deep Rolodex. “They can bring in expertise on . . . technical problems that we don’t see but anticipate,” he said. The prospect of Joy’s participation heightened the attraction. During two months of due diligence following the signing, the questions asked by Joy suggested that despite his spotty physics background he knew plenty about photovoltaics, as much as some experts, Naughton thought. Joy had also grown a company, having cofounded the IT giant Sun Microsystems. Bill Joy would be a good guy to have aboard, that was for sure.

Talks between KP and Boston College administrators began in late August—Boston College owned the rights to the nanocoax, which Kempa and the others had dreamed up and developed on the University’s time. When those discussions concluded, work could begin in earnest. Naughton was feeling good. “I’m confident,” he said, “that everything will come out rosy.”

 

The talks with Boston College took two months. The University, new to venture capital deals, was getting poor advice on what size chunk of Solasta to expect in return for giving Solasta the right to use the nanocoax technology, or so Naughton believed. In the end Boston College settled for a more than respectable 7 percent stake.

When Solasta finally went into business, in October 2006, it did so quietly, without ribbon cuttings or press events. KP, jealous of its brand, doesn’t advertise its failures; if Solasta did as well as hoped, there would be ample time for publicity. Naughton was happy, anyway, that the dealmaking was over, but he also regretted lost development time, two months when competitors might be working on the thick-thin problem while Solasta was tied up with business details. He couldn’t name a competitor with an idea close to Solasta’s, but, as he explained, “We’re afraid somebody will come out of left field . . . with a similar technology, who develops it sooner than we can do ours.”

The goal was to make up for lost time: to hire technical personnel and build and equip a laboratory, all by January 2007. Meanwhile, research would proceed, using borrowed facilities as required.

Turning carbon nanotubes into nanocoax involves three successive depositions—coating the nanotube first with metal, then with silicon, and finally with another layer of metal. Depositing the metals would require a device called a sputtering chamber, in which electrons bombard a metal target, creating a metallic cloud, some of which settles on the nanotubes. Solasta could use a sputtering chamber at Boston College for now. What the University lacked was something more exotic, a plasma-enhanced chemical vapor deposition (PECVD) chamber, inside of which silicon, in the form of silane, a silicon-containing gas, would be deposited on the nanotube with the aid of a powerful electrical field. Solasta, in the person of Jakub Rybczynski, the postdoctoral fellow who would become the startup’s senior process engineer, was renting time on PECVD devices at MIT, Harvard, and Penn State—wherever Rybczynski could schedule a couple of hours to lay down silicon.

Sadly, the occasional hour or two didn’t advance the project much. Getting their own PECVD chamber had to be Solasta’s first priority. A launch meeting was held in late October in a conference room in Higgins Hall. Naughton declared they would buy one of the chambers “even before we have someone to use it.”

At the long table sat Naughton, Rybczynski, Kempa, and Ren, along with Bill Joy and Mike Clary, Solasta’s new CEO, brought in by KP. With his quiet manner and casual dress—he went tieless and often wore jeans—Clary didn’t seem much like a corporate type, let alone a CEO, but he had put in 19 years at Sun Microsytems, where he served as a vice president and oversaw a research lab.

Joy made a crucial contribution at that meeting, suggesting that Solasta fabricate traditional solar cells, known as “planar devices” because of their flatness, alongside the nanocoax version, to show whether Kempa’s innovation was actually boosting efficiency—and afterwards Naughton exulted, “He’s psyched . . . so committed to this project!”

 

More meetings followed. In late November 2006, Mike Clary set a goal of two working nanocoax solar cells by mid-December. Also at the November meeting, Bill Joy called for the drawing up of two experimental plans, one to get to 5 percent efficiency and the other to get to an unheard-of 70 percent. At a meeting in late January 2007, Naughton and Bob Clark-Phelps, an engineer who worked briefly for Solasta, laid out a goal of 20 percent efficiency within the year, to be followed, Clary said, by a second round of funding—yet Solasta hadn’t even gotten into its lab cum office space, in a building in Newton’s Nonantum section. By late February, the hope was to move in by late March. At a meeting in late March, no move-in date was mentioned. Studs and drywall were in place but little more, it wasn’t clear exactly why, but Naughton blamed the building management.

Meanwhile, two postdocs had arrived from China, recruited via Ren’s network, with Solasta reimbursing Boston College for their salaries. They’d been brought in for their silicon expertise, but the PECVD device they needed for their work, bought secondhand at a steep discount and temporarily parked in Higgins, had yet to be used for a silicon deposition. It needed fine-tuning, apparently.

In early May, Naughton tried something new to nudge the build-out along and save a few dollars: He showed up in Nonantum and helped install plumbing. Solasta had hired licensed plumbers to hook up dangerous gases such as silane, but he felt comfortable doing nonexplosive gases. “We physicists,” he said, “are plumbers before we’re anything else.”

A focused-ion-beam image shows nanocoax layers. From bottom: silicon substrate, metal, amorphous silicon, and transparent conductor. Photograph: Greg McMahon

The analogy may have been a stretch, but Naughton really did have roots in the building trades. Growing up one of eight children of a plasterer in Rochester, New York, he had plastered his way through college and graduate school. As a boy, he won his school’s science prize, for building a scale model of an atomic reactor—with moving parts, including fuel rods—out of cardboard and other household supplies. But Naughton found science less compelling than sports. He spent hours playing hockey, wearing used skates and shin pads fashioned from old magazines. In college, he played the sport at the varsity level and didn’t concentrate in physics until he was forced to declare a major, at the end of junior year. Yet soon enough he realized he had the knack. Of the 140 journal articles, on topics such as superconduction and magnetic fields, that bear Naughton’s name, more than a dozen date to his graduate school years.

Frustration with the build-out peaked in early June 2007. Almost everything was ready now—gas cabinets, hookups, exhaust, sprinkler systems—but the fire department wouldn’t issue permits. One day, complained Naughton, the inspectors would say they couldn’t test a system unless it was turned on; the next day, they’d say you couldn’t turn the system on until it had been tested.

Last to go in were the fire alarms. Shortly after their installation, a signal from a cell phone set them off, and everyone working in the complex had to go out and stand in the rain, awaiting the arrival of fire trucks.

“It was ridiculous,” Naughton moaned, reporting on the incident a few days later.

 

Things started looking up late in June, when the city at last issued all needed permits. By mid-July Solasta already had its first working nanocoax solar cell, with 0.1 percent efficiency. By early August, efficiency had risen to 0.25 percent, the improvement due to the substitution of hydrogen for helium as the carrier gas that diluted the silane, for safety reasons, during silicon deposition.

Depositions were not being done in the second-hand PECVD chamber, however—it still wasn’t working. Instead, silicon deposition was taking place in a chamber built from spare parts by Ying Xu, one of the Chinese postdocs, at the suggestion of Zhifeng Ren. Ren lived by the motto “never get tied down to one system,” he said. In an interview in August Kempa credited him with saving the project, saying flatly that without the homemade chamber, “We would be nowhere.”
Of course, for a project of Solasta’s ambition, efficiencies of 0.25 percent were little better than nowhere. Nonetheless, 0.25 percent exceeded by 100 times the efficiency of the planar cells the postdocs and Rybczynski were fabricating under comparable conditions. Solasta’s configuration might actually be working. And better efficiency was coming soon.

 

The silicon in most solar cells contains additives, called dopants, usually boron and phosphorus, that dramatically increase voltage, the force that makes electrical currents flow. Solasta’s best sample, the 0.25 percent cell, was a primitive device using undoped silicon, but the postdocs Ying Xu and Yantao Gao, with long experience of doping, were ready to start this process as soon as Middlesex Gases delivered the necessary ingredients—any day now, in other words.

Thus, a meeting in mid-August 2007 had, on the whole, a cheery feel—on the whole, but not completely. CEO Clary warned that, at the current burn rate, funds would run out this time next year—a nightmarish prospect for the physicists, who, having barely gotten into the Nonantum lab, saw their progress in six weeks as near-miraculous.

Bill Joy took a more optimistic tack. “Let’s say by Christmas we have 7 or 8 percent,” he said, “and a road map to get to 12 and 24 percent. We’d have a story we could use to raise the money to move faster, by hiring more people.” The sooner they started the money hunt, the better, he said: “You’ve got ethanol companies trying to borrow $100 million to start manufacturing facilities, and they can’t. Six months ago, they could have. Solar is hot now, but it could change, like ethanol.”

On the other hand, he added, solar didn’t seem as likely to fade. With Germany aiming for a solar panel on every roof, and interest growing in China and India, unmet demand might be near-infinite. Joy, at 53, sounded like someone who knew whereof he spoke. He even had the look of an eccentric genius, pale and tall and very thin, with mussed hair and several days’ growth of beard.

 

Doping began in early September. “Our growers,” said Kempa, meaning the postdocs and Rybczynski, “are frantically working. We had to slow them down. They stay over the weekend, they don’t sleep—a typical immigrant attitude.”

By a mid-October meeting, the best nanocoax solar cell, the “champion,” was getting almost 2 percent efficiency. Dopant concentrations and silicon thickness hadn’t even been optimized yet, so further gains couldn’t be far behind.

Still, management wasn’t celebrating; in fact, the people from KP seemed distracted. In August, Joy had talked about a target of 8 percent by Christmas; now he was talking about getting to 15 percent by Christmas—an efficiency Solasta would never actually achieve and wouldn’t even approach for two more years. Clary was still fretting about the money clock, having moved his estimated cash zero date up a couple of months, to June 2008. During the meeting, Ren and Kempa needled the CEO. Whenever Clary made a technical suggestion or asked them to update him on an aspect of their work, they said, Oh, no, we can’t do that; that’s research! The tone was kept light and jokey, but they seemed to be reacting to Clary’s concern that the physicists hadn’t yet made the pivot from a scientific mindset to an engineering one, from what can we learn? to how do we get to 15 percent?

The cylindrical “canister,” in the University’s clean room, is part of a sputtering chamber used by the team to deposit metal layers.

Back in February, Joy had exhorted the team to “learn to fail faster.” It was a fashionable piece of business advice, but in context it meant abandoning ideas that didn’t deliver fast results, even if the physicists believed they would prove out in the end. Thus, an early collaboration between Solasta and a Spanish university team that had proposed to deposit silicon on Solasta’s nanotubes using a cheap, fast “wet chemistry” process was terminated after initial samples from the Spaniards were found to have short circuits.

Similarly, at the October meeting, Clary vetoed the idea of trying a new metal—instead of aluminum, tin—for one of the conductors. Ying Xu thought tin would sputter faster while conducting as well as aluminum, but Clary didn’t see the possible gain as being worth the time or potential complications.

Conflicts between business motives and scientific ones—between “what can we learn?” and “how can we get to 15 percent?”—would recur at Solasta. Such disputes always flare up when companies ask scientists to turn new technologies into products, says the New York University philosopher of science Michael Strevens. “Scientists are interested in the value of the knowledge they contribute for all time,” he says. “It’s quite natural that a company will want technologies to move quickly to commercial viability, whereas scientists aren’t all that interested in that. . . . Even if the product doesn’t go anywhere, the scientist still gets credit for the ideas behind it.”

Reflecting on this disconnect as it played out at Solasta, Naughton says, “We [scientists] never lacked for ideas. Maybe the company wasn’t the right forum for trying new ideas, but I’d rather have too many ideas than too few.”

“Kris Kempa was worried,” Clary says, “about publishing papers. That doesn’t win over investors. What wins over investors is efficiency numbers.”

 

While 15 percent efficiency remained elusive, the team came most of the way to 8 percent by March 2008.

The actual number was 5.7 percent, and they had gotten there thanks to a radical design change suggested by Kempa, who had put it through computer simulation trials. In the old configuration, the nanocoax was joined to a nano-antenna. In the new, the nanocoax doubled as a nano-antenna. Crucially, in the new design, indium tin oxide (ITO) replaced aluminum as the top metal layer. Electrically conductive but also transparent, ITO, like the metallic grid atop a commercial solar cell, could both harvest electrons and allow light through to the silicon. Thus, the new design, in addition to solving some materials problems that had stalled progress late in 2007, improved performance by allowing light collection along the full length of the nanocoax.

In late February, Rybczynski, now a Solasta engineer, was looking to squeeze a few more percentage points’ of efficiency from the new design by optimizing ITO deposition. As ITO gets more conductive, he explained, it becomes less transparent, and vice versa. He was aiming for the sweet spot, the ideal tradeoff between transparency and conductivity—which in practice meant finding the ideal oxygen-to-argon ratio for use inside the sputtering chamber.

The work involved twisting dials, inserting the samples and metal target into the chamber, waiting for the chamber to pump down to a vacuum, timing the metal deposition, measuring completed samples using high-tech test equipment. “It can be boring,” the affable Rybczynski confessed, smiling sheepishly. “You have to repeat things again and again with small changes.” A few weeks later, he elaborated, saying, “There are certain steps that are every time the same. Monday and Tuesday, we prepare the bottom contact. Wednesday, we grow the silicon. Thursday, we deposit the top contact. Friday, we measure. Every week, the same. But every week we’re making modifications and trying to optimize the conditions. When you’re doing pioneering work, you have to do it in small steps and change one parameter at a time.”

 

June 2008 arrived—mike clary’s predicted zero cash date—but Solasta would survive a few more months, thanks to a $900,000 grant from the Department of Energy. Efficiency was stuck at around 6 percent, though, roughly where it had been six months before, with progress held back by the mysterious problem of nanotube babies, dwarf versions of the full-size nanotubes that had suddenly begun appearing in the nanotube arrays coming out of Ren’s lab. Towered over by the other nanotubes, which were some 20 times their height, the babies didn’t get fully coated during depositions, resulting in samples with abundant short circuits. For months, in fact, most samples hadn’t produced any current at all. At a meeting back in April, Bill Joy had said, “This isn’t as easy to do as we thought.”

Nobody knew what was causing the babies, nothing had been changed in the nanotube fabrication process, but by the time they’d been made to go away, possibly by changing a few fabrication parameters, Solasta had switched from a nanotube-based solar cell to one using silicon nanopillars. Uniform in height and spacing, the pillars came from a company in North Carolina that manufactured them to specification. Efficiency might be stuck at 6 percent, but yield—the proportion of samples that actually worked—shot up dramatically with the nanopillars, from around 10 percent to something like 75 percent.

Progress on efficiency could now resume. The physicists were planning a couple of tweaks—increasing nanopillar length as a way of increasing light collection, and increasing the bang from the nanocoax by packing the pillars closer together. Before trying these ideas, however, the team had to get past a major roadblock. In their nanocoax fabrication, the silicon and especially the top metal layer, the ITO, had always gone on unevenly, with a thinner coating lower on the nanopillar or nanotube and a thicker coating up top, so that the final product, viewed through an electron microscope, looked like a squadron of soldiers in beefeater hats. The hats were blocking light from the lower part of the nanocoax, or maybe the unevenness of the coatings was interfering directly with the workings of the nanocoax. Either way, the unevenness—the “conformality problem,” as the physicists called it—seemed to be suppressing efficiency. Increasing the length of the nanopillars or the density of the array promised only to make things worse.

 

At the end of 2008, efficiency was still stuck at 6 percent and change. The team had tried zinc oxide instead of ITO for the top conductor, and while the zinc compound went on more uniformly, it hadn’t been conducting too well so far. At a meeting in December, though, the physicists were engrossed in a different issue: Electron microscope images had shown lines of nanopillars fallen like so many matchsticks in almost every recent sample. Had the samples all been scratched or dropped? Unlikely, since they’d come from different runs and had been stored in separate plastic cases. Bill Joy had stopped flying in for meetings—he either thought Solasta was doing fine without him, or he’d simply lost interest—but Mike Clary was there, and he tried to refocus on what he saw as the bigger picture, asking how Solasta could accelerate progress by increasing throughput, the number of samples cranked out in a week. Inevitably, he got drawn back into small-bore discussion, the fallen nanopillar detective story.

Meanwhile, the investor hunt kept being postponed, awaiting better efficiency, which would push up the value of company shares and by extension the size of any B-round capital infusion. Luckily, Solasta had captured another government grant, $2.7 million, from the National Renewable Energy Laboratory (NREL), the money to be paid out in installments as the team hit specified efficiency targets—the first three were 6.5, 8, and 10 percent.

 

The nanopillars stopped falling—after, and possibly owing to, a cleaning of the PECVD device—but in February 2009, efficiency remained around 6 percent, and samples still suffered from beefeater syndrome.

Then, in March, efficiency started creeping up for the first time in a year, thanks to a counterintuitive move. Instead of increasing the density and length of the nanopillars, as originally planned, the team had done the opposite, hoping that with shorter, more loosely packed pillars, the silicon and metals would go on more conformally. Having perfected their depositions with shorter, loose-packed pillars, they might eventually go back to taller and denser ones, further boosting efficiency. But for now they were closing in on 8 percent months ahead of the NREL schedule.

In May 2009, with money tight, Clary finally hit the road, pitching investors with a PowerPoint slide show. By June he had gotten 20 rejections out of some two dozen presentations, with the rest “moving through the due diligence and pull-back-the-covers stage,” he reported. With the way the economy was going, he said, “Investors are taking a longer look. Time is on their side, not ours.”
By July, two investors remained in the mix. One was still kicking tires; the other made a lowball money offer, along with what Clary thought were unreasonable demands. “A lot of times in these deals, you’ve got to say no,” he told a meeting at Solasta late that month. On the way out of the meeting room, he talked about the state of green tech investing. “Everyone’s just skittish as hell,” he said, “especially with the price of oil dropping. You can’t believe how hard it’s been.”

 

October in Solasta’s Nonantum meeting room. For a while now meetings have been more crowded, with added personnel including two lab techs, an engineer with a photovoltaics background, and three more doctoral level physicists. Engrossed in another detective story, the team is trying to determine the source of some contamination that seems to have gone away in recent sample runs. Clary is on speakerphone from Colorado, where he lives part-time, and from his tone of voice it’s clear he has little patience for this discussion. He wants to talk instead about how to get to 10 percent, from the present 8.5 or so. Solasta’s amorphous silicon is very close to the world’s best now, judging from the way their planar cells are functioning, so maybe it’s time to stop trying to squeeze more efficiency out of the silicon. Maybe it’s time to think about things like adding an antireflective coating, an ARC, to the top conductor.

The ARC is trivial, Kempa replies. Solasta can add one any time, in a matter of five minutes. Under the terms of the NREL grant, they don’t need to get to 10 percent until February, anyway.

“We have a game plan,” echoes Ren, “but the game has just started, and you are too anxious.”

 

Solasta’s final meeting, a conference call—Joy and Clary on the speaker and Naughton in his office in Higgins Hall—was scheduled with just an hour’s warning, on February 26, 2010. KP was pulling the plug on Solasta. Their analysts had reassessed the market for amorphous silicon photovoltaics—that was the extent of the explanation.

Bill Joy did not respond to messages requesting an interview about Solasta’s shutdown, but it seems likely that several external factors contributed to KP’s decision. First, in response to high worldwide demand, new facilities had sprung up recently to manufacture crystalline silicon, the price of which then began to drop, cutting into the price advantage enjoyed by amorphous silicon. According to Mike Clary, the demise of cap-and-trade legislation in the U.S. Senate was also a “huge” factor in KP’s move; by declining to apply a cost to carbon emissions, Clary says, the Senate, in effect, dramatically slowed renewable energy development. Also key to the decision was the failure to find a second investor. The shutdown, Clary sums up, was “more a commentary on the state of the market at the time” than on the Solasta technology.

Naughton blames the shutdown partly on unrealistic expectations that grew from KP’s roots in information technology. “In IT,” he says, “a half dozen engineers can hack code for three weeks straight and come out with something of value. And you can’t do that with materials. The whole venture capital community underestimated the realities of moving forward restricted by materials. The scientists, me included, underestimated that.”

Clary disagrees, saying, “KP’s expectations were realistic given the diligence that had been done on the [Solasta] technology. . . . KP stuck with it a long time. We never saw runaway success in terms of efficiency. We saw something that was good but not runaway success.” As to the idea, expressed by Naughton and Kempa, that Solasta had been undercapitalized, he says KP’s investment was intended “to prove there was an effect of a significant nature. I don’t think you need tens or twenties of millions to prove that.”

 

At the National Renewable Energy Laboratory news of Solasta’s shutdown was received with shock, says Martha Symko-Davies, who oversees the program that provided the company’s $2.7 million grant. Having just exceeded 10 percent at the time of the shutdown, Solasta was “making extremely good progress,” Symko-Davies says. “I’ve had other companies that are trying to do similar technologies, and Solasta was leaps and bounds ahead.” Of the fact that Solasta technology is now licensed by KP (as preferred shareholder) to a Chinese university, after millions of U.S. taxpayer dollars were invested in the firm, she says, “That pretty much kills me.” In the United States, she adds, “We do not have a strong enough system [for supporting green technologies] relative to the entire world, let alone China.”

Kris Kempa agrees. “China,” he says, “makes an enormous investment in green technology, and it’s long term compared to the American approach. An enormous amount of money is thrown at all sorts of technologies, even though they may not be the best ones in the end. But it creates an environment for vibrant research.”

Kempa argues that the effort to show fast results crowded out fundamental research that would have brought Solasta a better outcome. The last samples sent to NREL used such a low nanopillar height that they were barely Solasta devices at all; Kempa wonders whether their efficiency, a near world record for amorphous silicon at more than 10.5 percent, was actually coming from the nanocoax or just from Solasta’s growing prowess at laying down amorphous silicon. Instead of shortening the pillars, Solasta should have modified their shape, he says, a fundamental solution that would ultimately have allowed the team to start increasing pillar length, and thus efficiency. The technique had been tried in fall 2009 and showed promise of solving the conformality problems, but it was not the fastest way to 10 percent, and so it was back-burnered. “We [used] thousands of small tricks to avoid the best solution,” Kempa says. “Our device in the end became a patchwork of shortcuts.”

And yet Solasta doesn’t sound like a failure to Strevens, of NYU. “The fact that the technology was sold,” he says, “suggests that it was worth something and that these ideas will continue to be developed.”

Kempa himself says Solasta “was not a scientific failure, absolutely not. It was not even a technological failure. We still have the best nanostructured solar cell ever made.” Nonetheless, he doesn’t completely regret the company’s demise. “We were in such a pressure, such a stress,” he says. “To me it was a little bit of a relief.”

Kempa has hardly abandoned scientific research, the Solasta letdown notwithstanding. As ever, he has multiple projects ongoing, in fields ranging from nanoplasmonics to nano-optics to radio optics. Ren, for his part, has secured grants amounting to a yearly budget of $1.5 million to focus on energy conversion challenges over the next several years. And Mike Naughton is involved with half a dozen current research projects. In one, he and colleagues from the biology department are creating nanostructures to serve as sensors for detecting, among other things, cancer cells and chemical explosives. In another project, he’s working with organic materials that superconduct at low temperatures, and in yet another he’s hoping to develop nanostructured subretinal implants for use in treating blindness.

He seems to have moved past Solasta, but he still harbors complicated feelings about what transpired there. “If I try and stand back and look at it in the money person’s shoes, you’re in it to make money,” Naughton says. “When you look at it from my side, it’s ‘We put our heart and soul into this, and we could have used more run time.’”

David Reich is a writer in the Boston area.

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